Coordinate switching unit



2 Sheets-Sheet 1 lNVENTORS 4502a: M: CART/l) nae/am 44 C l/l V/CK BY AZORN G. F. M CARTHY ETAL COORDINATE SWITCHING UNIT cluuucluuunn cl June 21, 1960 Filed Jan. 19, 1955 June 21, 1960 e. F. MCCARTHY ETAL 2,942,068

COORDINATE SWITCHING UNIT 2 Sheets-Sheet 2 Filed Jan. 19, 1955 INVENTORS GEORGE E "cf/R76? I A? m Gl/L/V/CK ATT RN Unimd States t nt-O COORDINATE SWITCHING Filed Jan. 19, 1955, Se!- No. 482,806 isciaims. (cl. 179 47.54)

This invention relates to electrical switching systems and more particularly to a contact unit containing the active contacts of a coordinate or other multiple contact switch. I

The coordinate or cross-bar switch commonly used in automatic telephone switching systems is a rather delicately adjusted instrument requiring numerous parts as se'mbl'ed in a compact arrangement. The numerous contacts and selective actuating mechanism must, after assembly, be carefully adjusted for proper operation and since the switch is compact, this calls for painstaking manipulation in order not to disturb other adjusted parts. Where a part becomes 'worn or otherwise inoperative, the switch assembly usually requires a major disassembling job before the particular part can be'repaired or replaced, Furthermore, most contactsin such switches have a ruhf bing action which limits the life of the contacts and'also produces objectionable dust on the working parts, thus interfering with good contact operation.

One of the objects of this invention is to provide a new contact unit for a coordinate or other multiple contact switch which overcomes the above-mentioned and oth'er disadvantages of prior coordinate type switches. More particularly, the objects of the invention comprise the provision of the following: an active contact unit easily assembled without requiring contact adjustment'ya pres sure type contact arrangement, thus avoiding rubbing ac- .tion at the contacts; an active contact structure which is simple andeasy to manufacture and yet whil l is exeep tionally durable thereby insuring extremely long life; novel flexible ribbon contact strips and flexible contact pusher members therefor whereby multiple connections are insured with actuation of a single contact'pusher-ine'mher; and finally, units having multiple contact'strips' and selective pusher membersjsubstantiallyentirely enclosed,

the units being individually mounted for easy replacement in such systems as automaticjtele'phone and computer switching systems. v

One of the features of the invention is the arrangement of the active contacts as one or more flexible ribbon-like strips in a housing which is ope on one sideso as to overlie a row of passive contacts, the housing also containing pusher members corresponding in number to the number of passive contacts for movement relative thereto to engage the active conductor strips and effect closure between the strips and the passive contacts. The ribbon-like strips are provided with U-shaped'portions'to enhance flexing thereof whenthe strip is engaged byth'e pusher member, the strips being further provided dimpled contact portions'which are flashed with nickel and coated with a layer of rhodium jfor'makin'g pressure contact with the passive contact areas Each selective pusher member is arranged witha cushion-likejportion adapted to engage a plurality 'ofcondu'c'tive strips for multiple contact actuation, the cushion-like portion operating to insure satisfactory pressure contactfor all of the contact strips and further, to transmit pressure to the st ips directly proportional-to the pressure exerted upon "the 1C A 2,942,0o8

Patented June2l, 1960 2 pusher member. The housing of the unit is also provided with guiding slots for the pusher members and bridge elements between at least certain of the pusher members to prevent the action of one pusher from causing a'conductive strip to close with any other passive contacts than those directly beneath the pusher member. I

The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, in which: 7

Fig. 1 is a fragmentary view in side elevation of one panel'of a coordinate switch for use in an automatic telephone switching system embodying the Contact units of this invention;

Fig. 2 is a sectional view taken along line 2-2 of Fig. l;

V Fig. 3 is a view in plan of one section of the switch, the view being taken along line 3-3 of the central portion of Fig. 2;

Fig. 4 is an enlarged sectional view of the central portion of Fig. 2;

'Fig. 5 is a cross-sectional view taken along line 5--5 of Fig. 4;

Fig. 5A is an enlarged cross-sectional view of one of ther-ibbon strips shown in Fig. 5;

Fig. 6 is a view in side elevation of a modified form of pusher member; and, I

Fig. 7 is a view in elevation of the pusher member shown in Fig. 6.

For purposes of illustration, the invention is shown as a part of an automatic telephone switching system which comprises the subject matter of the copending application of Hatton and McCarthy 77-1, Serial No. 532,719, filed September 6, 1955, it being understood, however, that the invention is also useful in other switching systents wherever selective switching is required. Referring more particularly to Figs. 1 and 2, three contact units of this'invention are shown assembled on a passive-contact panel 1 at 2, 3 and 4. A fourth unit is removed from the section 5 'of the panel to illustrate the'details of the panel and the arrangement of the passive contacts. The panel comprises a base frame member 6 having thereon a layer ofi'nsulation 7. Horizontal multiple conductor strips.8 "are printed by known circuit printing techniques on the layer 7. These strips as shown are so arranged as to avoid the openi'ngs 9 through which selective fingers 10 extend. 'A second insulating layer 11 overlies the printed horizontal conductors 8 and contains thereon in groups passive contacts .12, 13, 14 and 15. Each such group of passive contacts is arranged in horizontal alignment and constitutes with adjacent groups of passive contacts a vertical row across the panel 1. The contact of each group such as 12-15 are connected through the insulating layer 11 to corresponding horizontal contact strips 8. While each group of passive contacts is shown to comprise four contacts, it will be recognized by those skilled in the art that each group may be less than four or greater than four depending upon the circuitry associated with each group.

From the foregoing description and reference to Figs. 1-5, it is clear that the groups of passive contacts are arranged in vertical sections and that each section has in overlying relation thereto a contact unit of this invention. The contact unit 3 shown in Fig. 2 is shown to comprise a housing having side walls 16 and 17, end walls 18 and 19 and a cover plate 2%). The bottom side of the housing is open so that when placed on the panel 1, it encloses a vertical row of passive contact groups. The open side, however, has bridge elements as indicated at 2 1 and 22, Fig. 4, so arranged as to lie at least between certain groups or as shown between adjacent groups of passive contacts. In overlying relation to each horizontal .3 group of passive contacts is a contact pusher member 23 guided by two grooves 24 and 25 contained in the side walls 16 and 17, Fig. 4. The pusher member comprises .a frame 26 which ,has a stem 27 adapted to extend through an opening 28 in the cover plate 20. The bottom portion of the frame 2648 provided with a resilient cushion pad 29, preferably of silicon rubber for engaging the ribbon contact strip. Each unit of the embodiment illustrated is provided with four ribbon contact strips 30, 31, 32 and 33. Eachstrip is preformed by a stamping operation and is mounted at its ends on the step portions 34 of the end walls 18 and 19, the strip being permitted to overlie the bridge elements such as indicated at 21V and 22.

Each strip is also provided with U-shaped portions 35 adjacentits ends which enhances the fiexi'bleness of the strip Qto permit movement ofthe strip by any one or more of the pusher members. As shown in Fig. 2, the ends of the ,strips are provided with terminals 36 and 37 which are receivable in the sockets 38 and 39 on the panel 1.

Referring to Fig. 1, the panel 1 is normally chosen of a size such that ten contact units are employed thereon.

Each contact group is provided with ten pusher members and the panel is provided with ten groups of horizontal passive contacts in each vertical row of passive contacts over which one of the contact units is placed. This provides for a possible selection of 100 different switching connections between the horizontal lines represented by the horizontal groups of passive contacts and those lines represented by the vertically disposed ribbon strips of each of the contact units. The horizontally disposed conductors which are connected to the passive contacts are connected from the panel to a terminal block 40. As previously mentioned the pusher members 23 are provided with stems 27 which extend through openings 28 in the cover plate of the contact unit- The fit between the stem and the opening is close so that there is little chance of dust working into the contact unit by way of the openings 28. The stem 27 is provided with a shoulder 41 which is adapted to be engaged by a selecting spring 42, Figs. 3 and 4. The spring 42 is anchored on a holding or vertical bar 43 as indicated at 44. While the spring 42 is shown to be S-shaped to insure proper resilience, the particular shape thereof is not limited since it may take any one of several different forms so long as it is sufficiently resilient and yet provide the desired interlocking operation between the stem of the pusher member 23 and the vertical bar 43. The position of the selecting spring 45 represents the normal positionof the selecting springs while the position of the spring 42 is that assumed upon actuation by a selecting finger 10. It will be understood by those skilled in the art that the sequence of operation is first the movement of the selecting finger 10 to move one or the other of the springs 42 or '45 to a selecting position overlying the shoulder 41 on the associated pusher member. The next movement is that of the vertical bar 43 which pivots downwardly against the actuated spring 42, thereby forcing the pusher member 23 against the ribbon contacts. These two movements are caused by electro-magnets, the selecting finger 10 being connected to a selecting horizontal bar 46 which in turn is connected to an armature 47 adapted to be attracted by one or the other of magnets 48 and 49. The horizontal bar 46 is pivoted by journals 5 1 and 52. As shown in Fig. 2, the magnet 48 has 'attractedthe armature 47, thereby causing the selecting finger 10 to move to the right, Figs. 2 and 4, thereby actuating the spring 42 to engage the shoulder 41 of pusher member 23.. Should the magnet 49 attract the armature 47, the selector finger 10 would then move to left and engage the spring 45. In association with each of the horizontal bars 46 is a horizontal normal contact unit 53 and a restoring spring 54 which are engaged by an arm 55 carried by the bar 46. The vertical bar 43 is pivoted on the frame of the panel 1 as indicated at journals 56 and 57, Figs. 1 and 2. Each of the bars 43 electromagnet 59 rocks the vertical holding bar 43 clockwise to engage spring 42 and force the pusher member against the associated ribbon contact strips 30-33. The resilience ofthe foot pad 29 of the pusher member 23 insures for open contact; pressure on each of the ribbon strips 30-33 forcing the contact dimples 60 into pressure engagement with the associated group of passive contacts 12-15. The holding -bar -43 remains in a holding position until its associated magnet 49 is deenergized whereupon the bar rotates counterclockwise to another position thereby releasing spring 42 and pusher member 23 to re turn to theirnormal positions, While the vertical bar 43 "is in holding position, the selecting finger 10 is left free to move for selective actuation of the spring 45. It should also be recognized that in an installation having more than onepanel 1 that the finger 10 may be extended on .the other 'side of the bar 46 for use in a second panel.

Each of the ribbon contact strips 30-33 is provided with longitudinal slots to render the strip more flexible and also toprovide the'strip with a pair of relatively independent contact dimples in overlying relation to the adjacent passive contact. Two such dimple contacts are shown at 60 and 61 in Fig. 5A. The strip is divided between the two dimple contacts by the slot 62. It is also preferred to have the U-shaped portion 35 slotted as indicated at 63. The material for the ribbon strips is preferably copper or brass clad at least on the contact side with a flash of nickel 60a and coated in the area of the dimple contact with a layer of rhodium 60b. The nickel flash found most suitable is .0003-5 inches thick 'while the rhodium layer was-preferably 20-25 millionths of an inch thick. These proportions are preferred since the nickel provides a good base for the rhodium and the latter does not' thin down or otherwise migrate under'repeated pressure contact engagement. The dim- ;pled portions of the strip only need be plated and coated with rhodium to provide a durable pressure type contact. In a test switch provided with such contacts a life test now in operation has performed over three million operations without failure. In Figs. 6 and 7, anotherform of pusher member is shown which is simpler and easier to manufacture than the one shown in Figs. 2, 4- and 5. The stem 64 and cross piece 65 are formed integral with the cross piece shaped with an arcuate recess 166 to receive a preformed resilient pad 67. The, resilient pad comprises a double "tubular stock which is readily extrudable and cut in lengths desired. In assembling the two parts, one of the tubular portions of the pad 67 is forced into the recess 66.

While the pad 67 is shown of double tubular stock, other shapes or even asingle tube may be used so long as it has a tubular or hollow portion exposed for unrestricted flexing when subjected to compressive action and thereby eqnalizethe pressure of the pusher member onto a plurality of associated ribboncontact. strips. One of the advantages of the tubular pressure pad is that its resilient resistance to compression is directly proportional, i.e., a straight line function, within rather 'wide limits as com.- pared to logarithmic pressure curve of a solid rpad. The recess 66 may also be of othershapes depending upon the shape of the pad stock selected. The member is guided in grooves formed by ridges 68 and 69 in the side wall 70. While we have described above the principles of our invention in connection with specific apparatus, his to be plearly understood thatthis description is made onlyby way of example and not as alimitation to the scope of our invention as set forth in the objects thereof'and in the accompanying claims.

- We claim:

1. A contact unit for switching purposes with respect to a panel carrying on the surface thereof a row of passive contacts comprising a housing supporting an active conductor lengthwise thereof, said housing :being open on one side to overlie said panel with said active conductor overlying in spaced relation-the .passive contacts of said row, and pusher members corresponding in number to the number of said passive contacts, :said. housing having means to locate each pusher member in overlying relation to said active conductor andin alignment with one of said passive contacts whereby movement of each of said members against said active conductor forces said active conductor into'contact engagement'with the corresponding passive contact, said housing including bridge-like elements extending laterally 'across the open side of the housing said bridge elements being adapted to normally confine said active conductor-inwandly of said housing, said bridge elements being disposed between adjacent pusher members whereby the active conductor is engaged by the two bridge elements adjacent the actuated pusher member to limit outward movement of said active conductor to the space between said two bridge elements.

2. A unit according to claim 1 wherein said active conductor comprises a fiat ribbon-like strip, said strip being provided With a U-shaped bend integral therewith to enhance flexing thereof when said strip is engaged by said pusher member.

3. The unit according to claim 1 wherein said active conductor comprises a flat ribbon-like strip and each of the contact engaging portions of said strip is slotted throughout said portion and the parts of the strips divided by the slot are each provided with a contact projection.

4. A unit according to claim 1 wherein said active conductor comprises a flat ribbon-like strip and each of the contact engaging portions of said strip is provided with a projection for contact purposes and the contact engaging projections of said strip are clad with a flash of nickel coated with a layer of rhodium.

5. A contact unit for switching purposes comprising a housing supporting a plurality of active conductors disposed in parallel relation lengthwise of said housing, said housing having openings on one side to overlie a row of passive contacts, said passive contacts being discrete flat strips spaced apart and said active conductors each being an elongated flat ribbon-like strip disposed in overlying relation to and crosswise of said passive contacts, pusher members corresponding in number to the number of said passive contacts, said housing having means to locate each pusher member in overlying relation to said active conductors and in alignment with one of said passive contacts whereby movement of each of said members against said active conductors forces said active conductors into contact engagement with the passive contact aligned with the activating pusher member.

6. The unit according to claim 5 wherein each pusher ember comprising a movable body supporting an elongated resilient contact pad crosswise of said active conductors, said pad having a portion shaped and disposed in exposed relation along the lengh thereof for contact engagement with a resilient compressive resistance distributed at points therealong directly proportional for a given range of movement of said member to the actuating pressure applied to said member.

7. The unit according to claim 5 wherein each contact pusher member has a resilient pad which includes an elongated tubular portion disposed crosswise of said active conductors for pressure engagement along one side wall of the tubular portion, the walls lateral to said one side wall being exposed for unrestricted flexing when said pad is subjected to compressive action Within a predetermined range of movement.

8. In switching apparatus of the character described having a panel containing a plurality of passive contacts arranged in a given plane, said passive contacts being disposed in groups with a number of such groups arranged in a row, the contacts of each group being spaced apart in a row transversely of the row of said. groups; a unit comprising a housing supported on'said panel in overlying relation with respectto a row ofsaid groups, a plurality of active conductors supported by'said housing lengthwis'e thereof and in spaced parallel relation to correspond with the spaced relation of the passive contacts in each of said groups, said housing being open on one side to expose'each of said conductors in overlying spaced relationwith respect to the corresponding passive contacts of said groups, pusher members corresponding in number to the number of said groups, and said housing having means to locate each pusher member in crosswise relation to said active conductors and in alignment with the. passive contacts of one of said groups and to guide said pusher member for movement against said active conductors to thereby force said active conductors into contact engagement with the passive contacts of said one group.

9. In switching apparatus of the character described, a unit according to claim 8, wherein the housing includes end walls to which the ends of said active conductors are secured, and each active conductor is provided with a length thereof disposed at an angle thereto to permit the conductor to be flexed laterally.

10. In switching apparatus of the character described, a unit according to claim 8, wherein each of said active conductors comprises ribbon-like strips, each such strip being provided with a U-shaped bend to enhance flexing.

11. In switching apparatus of the character described, a unit according to claim 7, wherein each of said active conductors comprises a ribbon-like strip with the portions thereof overlying said passive contacts being slotted throughout said portions and the two parts of the strips divided by the slot are each provided with a contact projection.

12. In switching apparatus of the character described, a unit according to claim 8, wherein said pusher member comprises a form carrying an elongated pad of resilient material for engagement crosswise of said active condoctors.

13. In switching apparatus of the character described, a unit according to claim 12, wherein said resilient material is silicon rubber.

14. In switching apparatus of the character described, a unit according to claim 8, wherein said housing includes bridge-like elements extending laterally across the open side of the housing, said elements being disposed between certain of pusher members whereby the active conductors are engaged by said elements when an associated pusher member is actuated thereby limiting contact engagement by the portion of said active conductors directly associated with the actuated pusher member.

15. In switching apparatus, a contact pusher member comprising a movable body supporting an elongated resilient contact pad disposed at right angles to the direction of movement of said body, said pad having a portion shaped and disposed in exposed relation along the length thereof for contact engagement with a resilient compressive resistance distributed at points therealong directly proportional for a given range of movement of said member to the actuating pressure applied to said member.

16. In switching apparatus, a contact pusher member having an elongated resilient pad which includes a tubular portion disposed at right angles to the direction of movement of said body for pressure engagement along one side wall thereof, the walls lateral to said one side wall being exposed for unrestricted flexing when said pad is subjected to compressive action within a predetermined range of movement.

17. A contact switching unit for coaction with a panel containing a plurality of passive contacts comprising a housing having side and end wallsto present a rectangular frame adapted to be supported in overlying relation Wit-hrespect to said panel, bridge elements disposed in spaced relation between'said side walls adjacent the panel side thereof, conductors supported lengthwise in said housing between said end walls, a plurality of pusher members, said side walls being provided with means to locate said pusher members in overlying relation to said conductors and for movement at right angles to said conductors, each pusher member being disposed in alignment with the space between adjacent ones of said bridge elements so that movement of a pusher member operates to flex said conductors between adjacent bridge members for contact engagement with the passive contacts of said panel.

18. An active contact unit for coaction with a panel containing a plurality of passive contacts, comprising a housing having side, end and top walls to present a rectangular frame, bridge elements being disposed in spaced relation crosswise of said frame between the bottom edge portions of said side walls, active conductors supported lengthwise in said housing between the end walls thereof in overlying relation to said bridge elements, a-plurality of pusher members, said side walls being provided with means to locate said pusher members in parallel relation with respect to said bridge elements and for movement respectively in a direction aligned with'the spacein between adjacent ones of said bridge elements for actuating movement against said active conductors to force the active conductors outwardly between adjacent bridge elements for contact engagement with passive contacts of said panel, said top wall having openings in alignment with said pusher members toperrnit selective actuation ofsaid pusher members.

References Cited in the file of this patent UNITED STATES PATENTS 1,541,343 Goff June 9, 1925 2,400,003 Hensel May 7, 1946 2,447,010 Harrison Aug. 17, 1948 2,516,772 Hickman July 25, 1950 2,517,022 Peek Aug. 1, 1950 2,730,594 Page Jan. 10, 1956 

